Thanks again
Lucy, Ta-ta, Bettinapple and Floodette for your thoughts!

They really helped me.
I wanted to think about it again since sometimes I'm so excited when I see something that I feel the need to immediatly buy it because I don't want it to go away. However, I've noticed it's always good to at least sleep over it and go for a loooong walk and get some fresh air. It helps me to get a feeling whether the item is really all that and whether I shouldn't get something else on the list instead. I much rather find an answer to that on a walk than when I sit in front of my computer browsing shopping sides...
So, I've slept over it. And I went on a five hour walk today!! And I took a decision: I'm gonna get it

I actually just ordered it! I like the trench that I own, and I do wear it nearly every day in spring / summer / early autumn. It is serving me extremely well. However, it has some details that made me think that next time I'd buy it just a little bit different. Now the new one has everything I wished for: It's single breasted, it doesn't have a belt yet its cut is female, it's a bit longer and it's a lighter fabric. My double breasted, belted, short, gabardine trench is great but it tends to be a tiny little bit bulky on my petite frame. So I'm gonna have that new trench sent to me and see if it's really as flattering as I think it is. (Besides, it's much cheaper than my original trench. It's from Burberry Brit and not from the main line).
Since the two styles are rather different I think I will have good use of both. Besides, my first one is in "Honey" and that second one is "Khaki Green". I also think a Burberry trench is such a classic that I can easily wear them for several years, so I consider my new one just as much of a long term investment like my old one. Burberry has NEVER let me down with quality, so I'm confident this one will be worth every penny.